cropped close up of a middle-aged woman's closed mouth and chin, and creases in the skin which have been formed by facial expressions over time
The findings could explain a lot about how our health changes over time (Picture: Getty Images)

Human understanding of the ageing process might have just been turned on its head, thanks to new research.

A scientific study which tracked molecules in blood, poo, and skin, mouth and nose swabs of people aged 25 to 75 found two major waves of age-related changes.

These spikes occurred around the age of 44 and then again at 60 – and could explain why certain health issues, like cardiovascular disease or musculoskeletal problems, tend to occur at certain ages.

So rather than ageing in a slow and steady process throughout your life, it seems instead it occurs in at least two accelerated bursts.

And the findings fit with previous evidence that suggests the risk of many age-related diseases doesn’t increase incrementally. The risk of developing illnesses like Alzheimer’s and cardiovascular disease increases steeply after the age of 60.

Professor Michael Snyder is a geneticist and director of the Center for Genomics and Personalized Medicine at Stanford University and senior author of the study.

Elderly couple
The findings were seen in men and women (Picture: Getty Images)

He told The Guardian: ‘We’re not just changing gradually over time. There are some really dramatic changes.

‘It turns out the mid-40s is a time of dramatic change, as is the early 60s – and that’s true no matter what class of molecules you look at.

The study tracked 108 volunteers who provided swabs and samples every few months for between one and six years.

Researchers looked at 135,000 different molecules (like proteins) and microbes (like bacteria, viruses and fungi) and found that most of them didn’t shift in a gradual, chronological way.

Instead, when looking for molecules and microbes with the largest shifts, they found these transformations usually happened when volunteers were in their mid-40s and early 60s.

The first wave of changes in their 40s included molecules linked to cardiovascular disease and the ability to metabolise caffeine, alcohol and lipids, AKA fats and oils.

The second wave, in the early 60s, saw changes in molecules related to immune regulation, carbohydrate metabolism, and kidney function.

Those linked to skin and muscle ageing changed at both time points.

At first it was thought the mid-40s spike might have been caused by perimenopausal woman skewing the results for the entire group – but then it was discovered that men were seeing similar shifts.

Dr Xiaotao Shen, another study author, said: ‘This suggests that while menopause or perimenopause may contribute to the changes observed in women in their mid-40s, there are likely other, more significant factors influencing these changes in both men and women.’

It’s hoped the findings could help to target interventions, for example increasing exercise when more rapid muscle loss is expected.

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